Math Skill: Using Parentheses
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Using Parentheses


When evaluating expressions that have parentheses, you always evaluate what is in the parentheses first.
When you don't evaluate what's in the parentheses first, you will get the wrong answer.
Let's take 3 × (8 - 5) as an example.

Right:  
3 × (8 - 5) =
3 × 3 = 9

  Evaluate what is in the parentheses first.
Wrong:  
3 × (8 - 5) =
3 × 8 - 5 =
24 - 5 = 19

  Ignoring parentheses gets the wrong answer.


If there is a pair of parentheses within a pair of parentheses, then evaluate what is in the inner pair of parentheses first.

Example:

(10 + (6 ÷ 2)) + (4 × 3)

(10 + (6 ÷ 2)) + (4 × 3) =       Evaluate the inner parentheses first
(10 + 3) + (4 × 3) =  
(10 + 3) + (4 × 3) =       Evalute the remaining parentheses
13 + 12 = 25

Complexity=2

1.   17 + (72 ÷ 8) = 2.   (4 × 1) + 19 =

Complexity=4

1.   9(2 × 5) = 2.   16 - (1 × 12) =

Complexity=6

1.   (5 + 7) + 8 = 2.   (25 ÷ 5)(18 ÷ 3) =

Answers


Complexity=2

#ProblemCorrect AnswerYour Answer
117 + (72 ÷ 8) =
Solution
72/8 => 9
Remove parentheses.
17 + 9 = 26
#ProblemCorrect AnswerYour Answer
2(4 × 1) + 19 =
Solution
4 × 1 = 4
Remove parentheses.
4 + 19 = 23

Complexity=4

#ProblemCorrect AnswerYour Answer
19(2 × 5) =
Solution
2 × 5 = 10
Remove parentheses.
9 × 10 = 90
#ProblemCorrect AnswerYour Answer
216 - (1 × 12) =
Solution
Remove parentheses.
16 - 12 = 4

Complexity=6

#ProblemCorrect AnswerYour Answer
1(5 + 7) + 8 =
Solution
5 + 7 = 12
Remove parentheses.
12 + 8 = 20
#ProblemCorrect AnswerYour Answer
2(25 ÷ 5)(18 ÷ 3) =
Solution
25/5 => 5
Remove parentheses.
18/3 => 6
Remove parentheses.
5 × 6 = 30